CO₂ Indicator

CO₂ sensor and traffic lights

Measure air quality and represent it with Traffic Light LEDs

Components

• MH-Z19C Infrared CO₂ Sensor: https://www.berrybase.de/mh-z19c-infrarot-co2-sensor-stecker-kabel
• LED Traffic lights, like https://www.berrybase.de/led-ampel-modul-mit-3x-8mm-led-rot-gelb-gruen-5v
• Raspberry Pi 4
• Female-Female Jumper Wires

Wiring

See Raspberry Pi GPIO Pin Layout: https://pinout.xyz/

MH-Z19C (CO₂ Sensor)	Raspberry Pi Pins
GND (Ground)	6 (Ground)
Vin	4 (5v Power)
RX	8 (GPIO 14/UART TX)
TX	10 (GPIO 15/UART RX)

Check CO₂ sensor device is registered as serial terminal: $ ls /dev/serial0

Traffic Lights (LED Output)	Raspberry Pi Pins
GND (Ground)	14 (Ground)
Red	15 (GPIO 22)
Yellow	13 (GPIO 27)
Green	16 (GPIO 23)

Deployment

The software can:

• set Traffic Light LEDs
• serve measurements via webserver

Run binary

Download binary from releases section

./co2indicator --server :8080 --led-pin.green=23 --led-pin.yellow=27 --led-pin.red=22 --device /dev/serial0

Check measurements: curl localhost:8080

Docker

docker run -it --rm --restart=unless-stopped \
      --device /dev/serial0 \
      --volume /sys/class/gpio:/sys/class/gpio \
      --volume /sys/devices/platform/soc/3f200000.gpio:/sys/devices/platform/soc/3f200000.gpio \
      ghcr.io/knrdl/co2indicator:edge \
      --led-pin.green=23 --led-pin.yellow=27 --led-pin.red=22

Dev Setup

Cross Compile for Raspi

cd src
GOOS=linux GOARCH=arm GOARM=7  go build
scp app pi@raspberrypi:/home/pi
ssh pi@raspberrypi '/home/pi/app --server :8080 --led-pin.green=23 --led-pin.yellow=27 --led-pin.red=22'